Two-stage hydrocarbon reforming process



TWO-STAGE HYDROCARBON REFORMING PRocEss Harold Beuther, Penn Hills, Robert E. Kline, Verona, and Robert C. Zabor, Glenshaw, Pa., assignors to Gulf Research 8; Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed Apr. 27, 1959, Ser. No. 808,885 3 Claims. (Cl. 20870) This invention relates to a method for upgrading catalytically cracked gasoline and more particularly to a method whereby a selected heavy fraction of catalytically cracked gasoline is subjected to catalytic conversion to produce high octane gasoline and naphthalene.

For a number of years catalytically cracked gasoline fractions of the entire gasoline boiling range, e.g., 100 to 450 B, have been considered to be satisfactory gasoline blending stocks. Recently, however, because of the demand for higher octane ratings and improved stability for blending stocks for premium gasoline, it has been recognized that only light catalytically cracked gasolines are satisfactory for premium gasoline blending stocks and the heavier fractions, i.e., fractions boiling above about 270 F. have been used only for the lower grades of gasoline or have been treated in various ways to improve their octane rating or stability. A need now exists for a process for successfully upgrading the heavy catalytically cracked gasoline to produce a blending stock suitable for premium gasoline. One possible way to upgrade the heavy catalytically cracked gasoline boiling above 270 F. is to catalytically reform the entire fraction. Another way is to caustic treat the heavy gasoline to remove substances that cause harmful engine deposits. These methods and other possible methods have various economic disadvantages, for example, low liquid product yield or inadequate upgrading of the charge stock.

We have now developed a new method for upgrading heavy catalytically cracked gasoline that offers important advantages over other possible ways of upgrading such stocks. Our new procedure has the advantage of producing from the heavy catalytically cracked gasoline a 400 F. end point gasoline of high octane rating and good stability which is suitable as a premium gasoline blending component. In addition to producing high quality gasoline in a good yield, our procedure has the important advantage of producing a high yield of the valuable chemical, naphthalene.

Our new process for upgrading catalytically cracked gasoline is based on the discovery that an excellent yield of high octane, 400 F. end point gasoline and V of naphthalene can be obtained if catalytically cracked gasoline is fractionally distilled to produce a selected heavy fraction which is then subjected to a selected catalytic conversion treatment. Our process in general comprises fractionally distilling a heavy catlaytically cracked gasoline, e.g., 270 F. to 450 F. fraction, to produce a heavy fraction having an initial boiling point in the range of 340 to 360 F. and consisting essentially of the C and heavier hydrocarbons of the catalytically cracked gasoline. The light fraction recovered from the distillation is either blended directly with the final gasoline product or is subjected to suitable upgrading treatment such as mild hydrogenation to remove sulfur and to saturate diolefins. The heavy fraction is subjected to severe catalytic conversion conditions in the presence of hydrogen and a hydrogenation-dehydrogenation catalyst such as fluidized molybdenum oxide on alumina. The catalytic conversion of States Patent 0 2,968,606 Patented Jan. 17, 1961 the heavy fraction is carried out at a temperature of about 900 to 1100 F., a pressure of to 1,000 pounds per square inch gauge, a liquid-hourly space velocity of 0.5 to 4.0 volumes of hydrocarbon per volume of catalyst per hour and at a hydrogen concentration of about 2,000 to 20,000 standard cubic feet per barrel of hydrocarbon. A 400 F. end point gasoline of higher octane rating than the original catalytically cracked gasoline is recovered as one product and a high yield of naphthalene is recovered as another product.

Our process provides a new method for upgrading heavy fractions of catalytically cracked gasoline. An example of such fractions is a fiuid catalytically cracked gasoline having a boiling range of 270 to 450 F. This type of gasoline is produced, for example, by catalytically cracking a straight run gas oil with the well-known fluidized silica-alumina cracking catalyst. The light fractions of the catalytically cracked product, especially cracked gasoline fractions boiling below about 270 F., are generally satisfactory for gasoline blending without further treatment. If desired, the light fractions can be subjected to mild hydrogen treatment to remove sulfur and to saturate diolefins or to more severe: hydrogenation for monoolefin saturation. However, the heavier fractions, i.e., fractions boiling above about 270 F., definitely require extensive further treatment to make products suitable as components of high quality gasoline. Catalytically cracked gasolines in the 270 to 450 F. boiling range are generally characterized by having octane ratings inadequate for premium gasoline, high sulfur content, and high content of diolefins, which results in poor stability. Although the heavy fractions of cracked gasolines produced by fiuid catalytic cracking of straight run gas oils or residual fractions of crude oil over silica-alumina catalysts are the most common charge stocks for which our process is applicable, heavy cracked gasolines produced by any of the fixed-bed or fluidized catalyst cracking processes using synthetic or natural silica-alumina type catalysts have components in common that make them amenable to upgrading by our process.

Our new procedure is based on the discovery that the fraction of catalytically cracked gasoline having an initial boiling point in the range of 340 to 360 IR, if subjected to severe catalytic reforming or hydrocracking conditions, will produce naphthalene and a high yield of high octane 400 F. end point gasoline. Therefore, we fractionally distill the heavy catalytically cracked gasoline, which normally will be a fraction having an initial boiling point of about 270 F., to produce a light fraction boiling below 340 F. to 360 F. and a heavy fraction boiling above 340 F. to 360 F. In this manner we segregate for further treatment a selected heavy fraction of the catalytically cracked gasoline which comprises substantially all of the C and heavier hydrocarbons and no more than negligible amounts of the C and lighter hydrocarbons.

We do not Wish to be bound by any theoretical explanation of the success of our procedure. However, it appears that our selection of a heavy fraction having an initial boiling point from 340 to 360 F. for severe hydroreforming or hydrocracking has several important advantages. In the first place, substantially all of the components of the heavy fraction contain at least 10 carbon atoms. Therefore, by hydrccracking these hydrocarbons we can produce from one heavy molecule two molecules of liquid gasoline components, that is, hydrocarbons having at least 5 carbon atoms in the molecule. Another advantage is that the selected heavy fraction contains most of the naphthalene precursors, e.g., indanes, tetralins, indenes and djhydronaphthalenes, that are present in catalytically cracked gasoline. This makes it possible for us to produce a high yield of naphthalene based on the material charged to catalytic conversion. The naphthalene is hfghly concentrated in a heavy fraction (e.g., 400 F. initial boiling point) of the conversion product of theC and heavier fraction. Because it is concentrated, the naphthalene can be separated from the gasoline components more efficiently than from very dilute concentrations, as in separating naphthalene in low concentrations from the product obtained by catalytic conversion of a wide boiling range catalytically cracked gasoline. Still anoth r advantage for applying our upgrading procedure to selected heavy cracked fractions boiling above 340 to 360 F. is that such fractions are the poorest in quality of the full range cracked gasoline and become increasingly poor in quality as the initial boiling point increases, the lower quality being apparent in many respects, for example, volatility, knock rating, sulfur content, stability, tendency to form harmful engine deposits, etc.

The catalytic conversion to which we subject the described cracked fraction employs severe reaction conditions leading to hydrocracking and dehydrogenation. The conversion is carried out in the presence of hydrogen and a hydroreforming or hydrocracking catalyst suitable for'use under severe conditions and capable of being frequently regenerated by burning off heavy carbonaceous deposits without serious loss of aitivity or selectivity. Such catalysts form a recognized class. .They comprise one or more of the metals of groups Va, VIa, or VIII of the periodic table and the oxides and sulfides of these metals. The preferred catalysts for our process are molybdenum, chromIum, tungsten, cobalt and nickel, the oxides or sulfides thereof or mixtures of two or more of such metals or their oxides or sulfides. Other metals within the mentioned groups, for example, platinum and palladium, have excellent catalytic characteristics for our process but have certain limitations, e.g., susceptibility to poisons such as sulfur, that make them less desirable than the indicated preferred catalysts. While the metals or their oxides or sulfides can be used alone, it is preferred to employ them with supports or carriers. Our preferred catalysts comprise a minor amount, e.g., 0.1 to 25 weight percent, of one or more of the indicated metals, oxides or sulfides, composited with a major amount of a support or carrier such as activated alumina, alumina gels, peptized alumina gels, silica gels, kieselguhr, silica-alumina gels, aged or deactivated silica-alumina cracking; catalysts, silica-magnesia gels, magnesia, titan-Ia, bauxite and the like. These supports should have moderate or at least low cracking activity but when composited with the hydrogenation-dehydrogenation metal component they should not form a composite catalyst that has such high cracking activity, as, for example, a fresh silica alumina cracking catalyst. A particularly suitable support comprises activated alumina containing a small amount of silica, for example, about 5 percent by weight, which improves the surface characteristics of the support. A particularly suitable catalyst is a fluidized catalyst composed of about weight percent molybdenum oxide on alumina stabilized with silica. In general, any of the known hydrogenation-dehydrogenation catalysts suitable for hydrocracking or hydroreforming under severe conditions involving high carbon laydown and frequent catalyst regeneration can be employed.

In our process the heavy olefinic fraction is contacted with the catalyst in the presence of hydrogen under rather severe hydroreforming or hydrocracking conditions. Severity of the reaction conditions is achieved mainly by maintaining a rather high reaction temperature and a rather low space velocity of the charge. The reaction temperature is in the range of 900 to l 100 F. and the liquid-hourly'space velocity is from 0.5 'to 4.0 volumes of hydrocarbon per volume of catalyst per hour (abbreviated hereinafter as LHSV and vol./vol./hr.). The pressure can extend over a considerable range but itis essential to maintain a reactor pressure of. at. least about 100 pounds per square inch gauge (abbreviated hereinafter as p.s.i.g.). Pressures in the range of 100 to 1,000 p.s.i.g. are suitable but pressures of 300 to 600 p.s.i.g. are preferred. .It is essential that the contact of the hydrocarbon charge with the catalyst be carried out in the presence of added hydrogen. Suitable hydrogen concentrations are in the range of 2,000 to 20,000 standard cubic feet of hydrogen per barrel of hydrocarbon (abbreviated hereinafter as s.c.f./bbl.).

It should be understood that not all possible combinations of conditions within the stated ranges will produce the same results. For instance, the use of the highest temperatures with the lowest space velocities of our disclosed ranges may cause excessive hydrocracking. Therefore, for temperatures near the upper end of the range, space velocities near the upper end of the range should be used. Likewise, if a total pressure near the lower end of the disclosed range is used, the hydrogen concentration should be well above the lower end of the disclosed range so that the partial pressure of hydrogen will not be too low. In any event, the combinationof reaction conditions must be such as to cause hydrocracking, dehydrogenation and dehydrocyclization of compo.- nents of the charge. The result of these reactions is to produce a reformed product containing 400 F. end point gasoline having a leaded Research octane rating of at least 100 in high yield, e.g., volume percent or higher based on 400 F. end point gasoline in the reforming charge and a high yield of naphthalene, namely, at least 4 weight percent based on the reforming charge.

The catalyst preferably is in a finely divided or powdered form and is maintained in the reaction zone in a fluidized or turbulent suspended state by gases flowing upwardly therethrough. The fluidized catalyst can be maintained either in a fixed fluidized bed or a moving fluidized bed. In a fixed-bed fluidized catalyst system, the catalyst remains continuously in the reactor. When the catalyst becomes deactivated the hydrocarbon charge is switched to another reactor and the catalyst is regenerated in situ in the reactor or is transferred to a regenerating vessel. In a moving bed fluidized catalyst system, a stream of catalyst is continuously withdrawn from the reactor, circulated to a regenerator vessel where carbon deposits are burned off and regenerated catalyst is continuously recirculated to the reactor. It is also within the scope of the invention to employ fixed-bed, stationary catalysts of the pelleted or granular type. However, heavy carbon laydown occurs in our process. Therefore, we prefer to use fluidized catalyst systems because of their superior regeneration characteristics.

The following examples describe different procedures thatwe have employed for upgrading catalytically cracked gasoline fractions. The results demonstrate the superiority of the process of the present invention for producing high quality 400 F. end point gasoline and naph- 'thalene.

EXAMPLE 1 The charge stock was a wide boiling range heavy fluid catalytically cracked or FCC gasoline fraction obtained by catalytic cracking of a straight run gas oil, and having an ASTM distillation range of 270 to 430 F. It is referred to hereinafter as a heavy FQCv gasoline, 270 430 F. This gasoline was subjected to catalytic reforming in a fluidized fixed-bed hydroreforming reactor containing a fluidized catalyst' composed of about 10.8 weight percent M00 on an alumina carrier containing about 5 weight percent silica. The reforming conditions were selected as being the optimum conditions for producing 400 F. endpoint gasoline from this particular charge stock in the most favorable yield-octane relationship. The reaction conditionsincluded a temperature'of 930 F., a pressure of 350 p.s.i.g., a liquid-hourly space velocity of 1.2 vol./ vol./ hr. and a hydrogen concentration of 6,000 standard cubic feet per barrel of hydrocarbon.

We have also subjected the same heavy FCC gasoline, 270-430 F., to upgrading by the process of our invention as described in the following examples.

EXAMPLES 2 AND 3 The heavy FCC gasoline was subjected to fractional distillation at an overhead vapor temperature of about 350 F. to obtain a 56 percent light fraction of 270- 350 F. boiling range and a 44 percent heavy fraction of 350-450 F. boiling range. The light fraction (Example 2) was subjected to mild hydrogen treatment over a fluidized molybdena-alumina catalyst at a temperature of 700 F., pressure of 75 p.s.i.g., liquid-hourly space velocity of 3 vol./vol./hr. and hydrogen concentration of 1200 s.c.f./bbl. The heavy fraction (Example 3) was subjected to severe reforming over a fluidized molybdenaalumina catalyst as described in Example 1 at conditions selected as optimum for producing 400 F. end point gasoline from this charge stock in the best yield-octane relationship. The reforming conditions included a temperature of 1010 F., a pressure of 350 p.s.i.g., a liquidhourly space velocity of 1.25 vol./vol./hr. and a hydrogen concentration of 3700 standard cubic feet per barrel of hydrocarbon. The reforming product was distilled to obtain a 400 F. end point gasoline and a heavier fraction having a high concentration of naphthalenes.

The table below provides a detailed comparison of the charge stocks and products of Examples 1, 2 and 3. The table also provides a comparison (Example 4) of the gasoline obtainable by blending the hydrotreated light fraction of Example 2 with the gasoline obtained by severe reforming of the heavy fraction of Example 3. As a further comparison, the table lists as Example 5 the characteristics of the gasoline obtainable by blending the untreated light fraction of Example 2 with the gasoline product of Example 3.

end point gasoline product at least as favorable as that of Example 1 and in addition provides a higher yield of naphthalene.

The table shows that catalytic reforming of the entire heavy FCC gasoline in Example 1 produced an 84.8 percent yield of 400 F. end point gasoline having a leaded Research octane rating of 101.2. By the term leaded Research octane rating we mean the knock rating of the indicated gasoline containing tetraethyl lead (abbreviated herein as TEL) in the amount of 3 cc. per gallon as determined by the CFRR or Reasearch Method for determining octane numbers. In our procedure the 270- 430 F. heavy gasoline was fractionally distilled to produce the light fraction of Example 2 which amounted to 56 percent of the full range fraction and had a leaded Research octane rating of 93.8 and the heavy fraction of Example 3 which amounted to 44 percent of the full range fraction and had a leaded Research octane rating of 90.9. Mild hydrotreating of the light fraction of Example 2 produced 100 percent yield of 400 F. end point gasoline product of decreased sulfur and gum content and of 96.3 leaded Research octane rating. We have indicated that by severely reforming the 350-450 F. fraction and distilling the reformate we obtain at least about volume percent yield, based on the 400 F. end point reforming charge, of 400 F. end point gasoline having a leaded Research octane rating of at least 100. The table shows that in Example 3 the yield of 400 F. end point gasoline obtained by reforming the: 350450 F. heavy fraction was 83.5 volume percent based on 400 F. end point reforming charge and had a leaded Research octane rating of 107.7.

By blending the hydrotreated light fraction of Example 2 and the reformed residual fraction of Example 3 we obtain in Example 4 a 10 RVP to 400 F. end point Table Example 1 2 3 4 5 Blend of H Blend of Un- Charge: Description Heavy Lt. 56% Frac. Hvy. 44% Treated Lt. treated Lt.

FCC of Hvy. FCC Frac. of Free. of Ex. 2 Fran. of Ex. 2 Gaso. Gaso. Hvy. FCC and Reformed and Reformed Gaso. Hvy. Free. of Hvy. Frac. of

Ex. 3 Ex. 3

Boiling Range, F 270-430 270350 Inspection of Full Range Fraction:

Octane Rating. CFRR, +3 cc. TEL/Gal 93. 6 93. 8 Naphthalene Content, Wt. Percent 0. 29 nil Total Naphthalenes, Wt. Percent 0. 74 ml Inspection of 400 F. EP Portion of Free 400 F. EP Gasoline, Vol. Percent 86 100 Sulfur, Wt. Percent 0.33 0.29 Existcnt Gum, Mg., 100 ml 35 17 Copper Dish Gum, Mg./100 ml 528 766 Product:

Yield of Gasoline (10 RVP 400 F. EP)

Vol. Percent of Fraction Charged. 84.8 117 55.7 90.0 90.0 Vol. Percent of 400 F. EP Gasoline in Fraction Charged 98. 6 3 117 83. 5 104. 7 104. 7 Yield of Naphthalenes, Wt. Percent of Charg Naphthalene .1 0. 58 nil 4. 43 1. 1. 95 Total Naphthnlenes 1.96 ml 8. 21 3. 52 3.52 Naphthalenes Content of 400-475 F. Fraction of Product, Wt. Percent- 24. 9 82. 1

Hydrotreated Light Fraction Inspection of 400 F. EP Gasoline Product:

Octane Rating of Gasoline Adjusted to 10 RVP:

CFRR, +3 cc. TEL/Gal 101. 2 96. 3 107. 7 101.3 100.9 Sulfur, Wt. Percent 0.015 0.18 0.007 0. 11 0.33 Eristent Gum, Mg./ ml 5 1 6 3 59 Copper Dish Gum, MgJlOO ml 9 90 13 56 723 Oxygen Stability, rnin 1,440 1, 440 680 Total naphthalenes=naphthalene, l-methyl and 2methylnaphthalenes; small amounts of other substituted naphthalenes not included.

1 RVP=adjusted to 10 lbs/sq. inch Reid vapor pressure by addition 01 butanes.

a 17% hutanes added to adjust to 10 lbs. RVP

The above table shows the advantages of our procedure over the Example 1 procedure of subjecting an entire 270 to 430 F. cracked gasoline fraction to severe catalytic reforming. The table shows that our procedure results in a yield-octane relationship for the 400 F.

blended gasoline of Example '4 has satisfactory characteristics with respect to sulfur, gum content and oxygen stability. Further improvement in these respects can be obtained by adding known gum and oxidation inhibitors to the gasoline and subjecting the gasoline to copper sweetening. Thus, the gasoline of Example 4 made by our procedure is about equal in quality to that produced by reforming the wide boiling range fraction in Example 'l'and'the yield is considerably higher.

' Most importantly, the table shows that our method produces a superior yield of naphthalene and methylnaphthalenes. A comparison of the yields based on the "full range 270-430 F. charge stock can be obtained by .comparing Examples 1 and 4. This shows an almost twofold superiority for our procedure. The yield of total naphthalenes for Example 4 is 3.52 percent as compared with 1.96 percent for Example 1.

The yield of naphthalene and methylnaphthalenes based only on the heavy fraction charged to the severe reforming stage in our process will be at least about 4 weight percent. The table shows that in our Example 3 "the yield of naphthalene was 4.43 weight percent and the yield of total naphthalenes was 8.21 weight percent of the heavy fraction charged.

Furthermore, our procedure has the advantage that the naphthalene is highly concentrated in the heavy ends of the product obtained by sereve reforming of the selected heavy fraction of the catalytically cracked gasoline. The end point of the reformed product will be higher than that of the charge to the reforming stage because of poly merization and/ or alkylation reactions. Substantially all of the naphthalenes in the product will be in a fraction boilingin the range of about 400 to 475 F. The reformed product can be distilled to obtain a heavy fraction having an initial boiling point above 400 F. which contains at least about 80 weight percent total naphthalenes. Specifically, in Example 3 the 400 to 475 F. fraction of the reformed product contained 82.1 weight percent total naphthalenes, including naphthalene and methylnaphthalenes. The residue boiling above 475 F. will normally be a very small part of the total product obtained by reforming a 450 F. end point catalytically cracked gasoline in accordance with our procedure and will contain little if any naphthalenes. In Example 3 the material boiling above 475 F. amounted to only about 3.4 percent of the reforming charge and was substantially free of naphthaleneand methylnaphthalenes.

Under Example of the table are reported the characteristics of the gasoline obtained by blending the untreated light fraction of Example '2 with the reformed heavy fraction of Example 3. This product is less satisfactory than that of Exarnple 4 with respect to stability and sulfur content but its yield-octane relationship is more favorable than that of Example 1.

Examples 1 through 5 demonstrate the advantages of subjecting a narrow boiling range heavy cracked gasoline to severe catalytic reforming to produce high octane gasoline and naphthalene. The examples show the superiority of the narrow boiling range heavy cracked naphtha for this purpose as compared with a wide boiling range cracked naphtha. The narrow boiling range heavy cracked naphtha of Example 3 is also superior to other types of heavy naphtha fractions of similar boiling range for production of high octane gasoline and naphthalene by sereve catalytic reforming. This is demonstrated by the results obtainable in similar catalytic reforming of a heavy fraction of the product obtained by catalytic reforming a straight run naphtha over a platinum-aluminahalogen catalyst. Such a heavy reformate fraction of 320 to 460 F. boiling range has been subjected to severe catalytic reforming over a fluidized molybdenaalumina catalyst at 1050 F., 100 p.s.i.g., LHSV of 1 vol./.vol,/hr. and at .a hydrogen concentration of 3700 s.c.f./bbl. The yield of naphthalene in the product was 2.84 weight percent based on the total charge, which contained 1.04 weight percent naphthalene. 'The yield of 'l0'RVP-400 F. end point gasoline based on 400F. endv point gasoline inthe charge was only 63.4 volume percent when the octane rating of this gasoline was 108.2, Research, leaded. The overall results are less satisfactory than those demonstrated by our procedures of Examples 3, 4 and 5.

Severe catalytic reforming of a narrow boiling range heavy straight run naphtha is likewise inferior to our procedure. For example, a heavy Kuwait straight runnaphtha of 350 to 420 F. boiling range has been subjected to catalytic reforming over a fluidized molybdena-- alumina catalyst at 250 p.s.i.g., LHSV of 1 VOlL/VOl./h1.,. hydrogen concentration of 5,000 s.c.f./bbl. and at'tem-- peratures in the range of 900 to 950 F. The yieldoctane curve for the 400 F. end point gasoline obtained by severe reforming of this stock compares unfavorably with our results. For a yield comparable to the 83.5 volume percent yield obtained in our Example 3 theleaded Research octane rating of the product is only 97.1 as compared with 107.7 for our product of Example 3. In the reforming of this straight run stock it is possible to obtain a 10 RV? to 400 F. end point gasoline with a leaded Research octane rating of 101.4 but the yield is only 72 volume percent based on the 400 F. end point gasoline in the fraction charged.

We have disclosed that fractions of the catalytically cracked gasoline lighter than the fraction of 3.50 to 450 F. boiling range which we subject to .severe catalytic reforming can be blended directly with the final gasoline product. Fractions boiling below about 270 F. require little or no further treatment but for the, highest quality of final blended product it will generally be preferred tosubject the fraction boiling from about 270 F. to the initial boiling point of our selected heavy fraction to mild hydrogen treatment to reduce the sulfur content and improve the stability. Mild hydrogen treatment comprises contacting the light fraction (e.g., 270 to 340 F. boiling range) wit-h a hydrogenation catalyst such as. molybdena-alumina, nickel-cobalt-molybdena on alumina,

cobalt-molybdena on alumina, or the like, at a temperature from 600 to 750 F., a pressure of from 50 to 500 p.s.i.g., a liquid-hourly space velocity from 2 to 8 vol./vol./hr. and in a hydrogen concentration of 1,000 to 2,500 s.c.f./bbl. Specific conditions within these ranges can be selected according to the severity desired for the hydrogen treatment. The more severe conditions will produce a more stable gasoline and one having lower sulfur content than the less severe conditions but will reduce the octanerating of thehydrogen-treated product.

Obviously many modifications and variations of the in vention as hereinbefore set forth may be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated in the appended claims.

-We claim:

1. The process which comprises fractionally distilling 'a catalytical'ly cracked gasoline to obtain a heavy fraction thereof having an initial boiling point in the range of 340 to 360 F., said heavy fraction consisting essentially of compounds containing at least 10 carbon atoms in the molecule and comprising substantially all of the C and heavier hydrocarbons of said catalytically cracked gasoline, contacting said heavy fraction with a reforming-bydrocracking catalyst under severe reforming conditions including a temperatureof "900 to 1100" F., a liquid-hourly space velocity of 0.5 to 4.0 vol./vol./ hr., a pressure of to 1,000 p.s.i.g. and in the presence of hydrogen in a concentration of at least 2,000 s.c.f./bbl., and recovering a reforming product comprising high octane gasoline and naphthalene in a yield of atleast 4 weight percent based on. the heavy fraction charged.

2. The process which comprises subjecting a straight run gas oil to fluidized catalytic cracking, recovering from the catalytically cracked gasoline product a heavy fraction thereof having an initial boiling point from 340 to 360 F. and consisting essentially of hydrocarbons having at least carbon atoms in the molecule, contacting said heavy fraction with a fluidized molybdenum oxidealumina catalyst under severe reforming conditions ineluding a temperature of 900 to 1100" F., a liquidhourly space velocity of 0.5 to 4.0 vol./vol./hr., a pressure of 100 to 1,000 p.s.i.g. and in the presence of hydrogen in a concentration of at least 2,000 s.c.f./bb1., fractionally distilling the reforming product, recovering from the distillation a 400 F. end point gasoline in a yield of at least 80 volume percent based on the 400 F. end point gasoline in the reforming charge and having a leaded Research octane rating of at least 100, also recovering from the distillation of the reforming product a heavy fraction having an initial boiling point above 400 F., recovering naphthalene from said latter fraction and blending said 400 F. end point gasoline with a light fraction of the catalytically cracked product.

3. The process which comprises fractionally distilling a catalytically cracked gasoline having an initial boiling point of about 270 F. to obtain at least one light fraction thereof consisting essentially of C and lighter hydrocarbons and a heavy fraction having an initial boiling point of 340 to 360 F. and containing substantially all of the C and higher hydrocarbons of said cracked gasoline, contacting a light fraction of said cracked gasoline having an initial boiling point of about 270 F. with a hydrogenating catalyst under mild hydrogen-treating conditions including a temperature of 600 to 750 F., a liquid-hourly space velocity of 2 to 8 vol./vol./l1r., a pressure of to 500 p.s.i.g. and in the presence of hydrogen in a concentration of 1,000 to 2,500's.c.f./bb1., contacting said heavy fraction with a fluidized molybdenum oxide-alumina catalyst under severe reforming con ditions including a temperature of 900 to 1100 F., a liquid-hourly space velocity of 0.5 to 4.0 vol./vol./hr., a pressure of 100 to 1,000 p.s.i.g. and in the presence of hydrogen in a concentration of at least 2,000 s.c.f./bbl., fractionally distilling the reformed product, recovering from the distillation a 400 F. end point gasoline having a leaded Research octane rating of at least 100 and a heavier fraction of which the portion boiling in the range 400 to 475 F. contains at least about weight percent total naphthalenes, blending said 400 F. end point gasoline of the reformed product with the hydrogen-treated light fraction of the catalytically cracked gasoline and recovering naphthalene from the heavier .fraction of said reformed product.

References Cited in the file of this patent UNITED STATES PATENTS 2,367,527 Ridgway Jan. 16, 1945 2,377,107 Rollman May 29, 1945 2,425,960 Schulze Aug. 19, 1947 

1. THE PROCESS WHICH COMPRISES FRACTIONALLY DISTILLING A CATALYTICALLY CRACKED GASOLINE TO OBTAIN A HEAVY FRACTION THEREOF HAVING AN INITIAL BOILING POINT IN THE RANGE OF 340* TO 360*F., SAID HEAVY FRACTION CONSISTING ESSENTIALLY OF COMPOUNDS CONTAINING AT LEAST 10 CARBON ATOMS IN THE MOLECULE AND COMPRISING SUBSTANTIALLY ALL OF THE C10 AND HEAVIER HYDROCARBONS OF SAID CATALYTICALLY CRACKED GASOLINE, CONTACTING SAID HEAVY FRACTON WITH A REFORMING-HYDROCRACKING CATALYST UNDER SEVERE REFORMING CONDITIONS INCLUDING A TEMPERATURE OF 900* TO 1100* F., A LIQUID-HOURLY SPACE VELOCITY OF 0.5 TO 4.0 VOL/VOL./ HR., A PRESSURE OF 100 TO 1,000 P.S.I.G. AND IN THE PRESENCE OF HYDROGEN IN A CONCENTRATION OF AT LEAST 2,000 S.C.F/BBL., AND RECOVERING A REFORMING PRODUCT COMPRISING HIGH OCTANE GASOLINE AND NAPHTHALENE IN A YIELD OF AT LEAST 4 WEIGHT PERCENT BASED ON THE HEAVY FRACTION CHARGED. 